But there's one huge advantage of retrofocus lenses - telecentricity. Retrofocus lenses automatically are quite telecentric, which means that rays of light hit the sensor at a perpendicular angle even at the edges; non-telecentric lenses don't have this property. With film, it didn't matter, because they would still penetrate the film layer and be recorded; the physical depth of the sensor makes that a lot more difficult, and without special measures, much of the light at the edges of the frame would be lost, leading to massive vignetting in effect. That's why it took Leica quite a while to dip their toes into digital with the M, and when they did, the M8 was APS-C - and so on with lens coding etc.

The way round it has been with the design of microlenses angled towards the centre, allied with greater ampliciation of edges - and for most mirrorless designs, not going full frame, and having lenses specifically designed with this in mind - the 11-22 being a great example of how well it can be done.

Incidentally, the issue of sensor depth and not-perpendicular image rays would appear to be the reason for the size of Sigma's Foveon sensor - the depth being more significant and critical with that design.

Conceptually this may be true. But practically, it's a non-issue. Just look at today's non-retrofocus lenses on today's non-mirrored digital cameras. Is it an issue? No. From the user perspective, we just see compact lenses for mirrorless cameras that deliver great performance. If that's someone's reason for sticking with DSLRs, then I'd say that's a rather false reason. Go use any of today's mirrorless cameras , and you won't find this to be an issue compared to DSLR.